Escherichia coli is the most common gram-negative organism causing nosocomial bacteremia in infants, children and adults. E. coli is also the most common cause of gram-negative bacteremia in patients with cancer and leukemia as well as in veterans and elderly patients. The mortality and morbidity associated with E. coli bacteremia is substantial. For example, E. coli sepsis is associated with estimated 40,000 deaths each year at a cost of 2.0 billion dollars per annum in the US (67). A recent report has also shown that community-acquired bacteremia is responsible for at least one third of deaths in infants and children in sub-Saharan Africa, and E. coli was the most common cause for bacteremia in infants (68).
At present, there are no preventive measures available against E. coli bacteremia. A major contributing factor is an incomplete understanding of the pathogenesis of E. coli bacteremia, e.g., what are the microbial determinants contributing to E. coli bacteremia. Previous studies have identified several microbial factors associated with the pathogenesis of E. coli bacteremia. For example, the K1 capsular polysaccharide and O-lipopolysaccharide (LPS) have previously been shown to be critical for induction of E. coli bacteremia. However, the feasibility of using the K1 capsule and O-LPS for the prevention of E. coli bacteremia, has not been realized, and where attempted has been shown to be limited.
Thus, there remains a need in the art for the identification of microbial targets for the prevention of bacterial infections, and in particular E. coli extraintestinal infections.